This invention relates to wood preservative and waterproofing compositions containing an amine oxide and an aqueous copper amine complex.
Chromated copper arsenate is commonly employed as a wood preservative. The chromium oxidizes the wood and generates sites for fixing the copper and arsenic to the wood. Although copper is a highly effective wood preservative, some fungi are resistant to its biocidal activity. The arsenic serves to control fungi that are tolerant to copper and protect the wood against wood destroying insects.
In recent years, however, many concerns have been raised regarding contamination of the environment by chromium and arsenic. There is also increasing concern regarding disposal of wood treated with chromated copper arsenate and halides.
As a result, there is a need for copper containing wood preservatives which do not contain chromium, arsenic, or halides and are environmentally friendly, yet have similar wood preservative properties to chromated copper arsenate.
Applicants have discovered that amine oxides enhance the performance of aqueous copper amine complexes as wood preservatives and provide waterproofing properties. The present invention provides a composition comprising an amine oxide and an aqueous copper amine complex.
Another embodiment of the present invention is a method for preserving and/or waterproofing a wood substrate by contacting the composition with the wood substrate.
Yet another embodiment is an article comprising a wood substrate and the composition of the present invention.
This composition has high efficacy against fungi, including copper tolerant fungi such as brown rot and soft rot. Also, the composition is phase stable at high concentrations without the need for polyamines or other stabilizers known in the prior art. The amine oxide in the composition may impart waterproofing properties. The composition of the present invention is typically free of ionic halides, in particular chlorides, and is environmentally friendly.
The present invention provides a composition comprising an amine oxide and an aqueous copper amine complex.
The amine oxide may be a trialkylamine oxide; N-alkylated cyclic amine oxide; a dialkylpiperazine di-N-oxide; an alkyldi(poly(oxyalkylene))amine oxide; a dialkylbenzylamine oxide; a fatty acylaminopropyldimethylamine oxide; a diamine dioxide; a triamine trioxide; and any combination of any of the foregoing.
Preferred trialkylamine oxides have the formula R1R2R3Nxe2x86x92O, where R1 is a linear, branched, cyclic or any combination thereof C6 to C40 saturated or unsaturated group; and R2 and R3 independently are linear, branched, or any combination thereof C1 to C40 saturated or unsaturated groups. R1, R2, and R3 independently may be alkyl, alkenyl, or alkynyl groups. R1 is preferably a C8 to C40 group. More preferably, R1 is a linear, branched, cyclic or any combination thereof C8 to C22 saturated or unsaturated group, such as coco, hydrogenated tallow, soya, decyl, and hexadecyl; and R2 and R3 independently arc linear, branched, or any combination thereof C1 to C22 saturated or unsaturated groups, such as coco, hydrogenated tallow (which is typically about 70-75% by weight of C1. alkyl, about 20-25% by weight of C16 alkyl, and traces of lower derivatives), soya, decyl, and hexadecyl.
A preferred trialkylamine oxide is a dialkylmethylamine oxide having the formula R1R2CH3Nxe2x86x92O, where R1 and R2 are defined as above. Another preferred trialkylamine oxide is an alkyldimethylamine oxide having the formula R1(CH3)2Nxe2x86x92O, where R1 is defined as above. Suitable alkyldimethylamine oxides include, but are not limited to, a C10 alkyldimethylamine oxide, a C12-C14 alkyldimethylamine oxide, a C16-C18 alkyldimethylamine oxide, and any combination of any of the foregoing.
Preferred N-alkylated cyclic amine oxides have the formula R4R5R6Nxe2x86x92O where R4 is defined as R1 above and R5 and R6 are linked to form a cyclic group. The cyclic group typically contains from about 4 to about 10 carbon atoms and may optionally contain oxygen, sulfur, nitrogen, or any combination of any of the foregoing. More preferred N-alkylated cyclic amine oxides include, but are not limited to, an alkylmorpholine N-oxide, a dialkylpiperazine di-N-oxide, and any combination of any of the foregoing.
Preferred alkylmorpholine N-oxides have the formula 
where
R7 is defined as R1 above.
Preferred dialkylpiperazine di-N-oxides have the formula 
where
R8 is defined as R1 above and R9 is defined as R2 above.
Preferred alkyldi(poly(oxyalkylene))amine oxides have the formula 
where
R10 is defined as R1 above; R11 and R12 independently are H or CH3; and m and n independently are integers from about 1 to about 10.
Preferred dialkylbenzylamine oxides have the formula R10R11R12Nxe2x86x92O, where R10 is defined as R1 above; R11 is defined as R2 above; and R12 is benzyl. More preferred dialkylbenzylamine oxides include, but are not limited to, alkylbenzylmethylamine oxides having the formula R10R12CH3Nxe2x86x92O where R10 and R12 are defined as above.
Preferred fatty acylaminodimethylpropylamine oxides have the formula 
where
R13 is defined as R1 above.
Preferred diamine dioxides have the formula 
where
R14 is defined as R1 above; and m is an integer from about 1 to about 10.
Preferred triamine trioxides have the formula 
where
R15 is defined as R1 above; and m and n independently are integers from about 1 to about 10.
Long chain (C16 or greater) amine oxides, such as hexadecylamine oxides, octadecyldimethylamine oxides, and hydrogenated tallow amine oxides, are particularly preferable for imparting waterproofing properties to the composition. Short chain (C14 and shorter) amine oxides, such as decyldimethylamine oxides, dodecyldimethylaine oxides, and tetradecyldimethylamine oxides, aide in solubilizing the aqueous copper amine complex and long chain amine oxides, and are efficient stabilizers.
Preferably, the composition contains a mixture of C16-C18, long chain amine oxides to impart waterproofing properties and C10-C14 short chain amino oxides to solubilize the long chain amine oxides. Typically, such a mixture comprises at least 50% by weight of long chain amine oxide based upon 100% total weight of amine oxides.
A blend of long chain and short chain amine oxides is also contemplated in one embodiment of the present invention. The long chain amine oxides may be blended with the short chain amine oxides in a ratio of about from about 1:10 to 10:1 in order to yield a stable preservative solution as described herein. For example, in a preferred embodiment, a mixture of long chain (e.g., C16) and short chain (e.g., C12) amine oxides in a ratio of from about 1:1 to about 5:1 and particularly a ratio of about 5:2 provides the desired dissolution of copper amine complex to provide a stable solution. The appropriate ratio of long to short chain amine oxides can be readily determined by those of skill in the art using methods provided herein to test solubility and stability of the solutions.
The copper amine complex generally contains a water soluble amine. Suitable copper amine complexes include, but are not limited to, ammonium/copper complexes, ethanolamine/copper complexes, diethanolamine/copper complexes, triethanolamine/copper complexes, diethylamine/copper complexes, ethylene diamine/copper complexes, or any combination of any of the foregoing.
The weight ratio of copper (expressed as copper oxide) to amine oxide in the composition generally ranges from about 1:0.01 to about 1:50 and preferably ranges from about 1:0.5 to about 1:2. According to one embodiment, the weight ratio ranges from about 1:0.1 to about 1:5. In embodiments of the composition which include at least two amine oxides, the weight ratio of copper (expressed as copper oxide) to total amine oxide preferably ranges from about 1:1 to about 1:2.
The composition may further comprise a fatty amine having at least one C8-C40 alkyl group to further enhance the wood preserving and waterproofing performance of the composition. Suitable fatty amines include, but are not limited to, dialkylmethylamines; alkyldimethylamines and in particular (C8 to C18) alkyldimethylamines; dialkylamines (i.e. secondary amines); alkyl propylene diamines; and any combination of any of the foregoing. A non-limiting example of a suitable dialkylmethylamine is N,N-dioctyl-N-methylamine. Examples of suitable alkyldimethylamines include, but are not limited to, N-lauryl-N,N-dimethylamine, N-dodecyl-N,N-dimethylamine, N-hexadecyl-N,N-dimethylamine, Noctadecyl-N,N-dimethylamine, cocodimethylamine, hydrogenated tallow dimethyl amine, and any combination of any of the foregoing. A non-limiting example of a dialkylamine is N,N-dioctylamine. Examples of suitable alkyl propylene diamines include, but are not limited to, N-dodecyl propylene diamine, N-coco propylene diamine, and any combination of any of the foregoing. While most prior art copper compositions which contain fatty amines have low phase stability and require polyamines and other adjuvants to increase phase stability, compositions of the present invention which include fatty amines have high phase stability and do not require polyamines or other adjuvants.
The weight ratio of amine oxide to fatty amine in the composition broadly ranges from about 4:1 to about 1:4. A preferred embodiment of the invention has a weight ratio of cocodimethylamine oxide to cocodimethylamine or N-dodecyl propane diamine of about 1:1. For such an embodiment, the preferred weight ratio of copper (expressed as copper oxide) to amine oxide to fatty amine is about 2:1:1.
The composition is typically substantially free of ionic halides and preferably contain less than about 10 ppm (w/w) of ionic halides. In contrast, ammonia copper quats in wood treating solutions generally contain about 500 ppm chloride.
The composition may include a solvent (in addition to water), such as water miscible solvents including, but not limited to, alcohols, such as ethanol and glycols (e.g. ethylene glycol); esters; ethers, such as ethyl ether; polyethers; amine; and any combination of the foregoing.
The composition, when in concentrated form, preferably contains from about 5 to 30% by weight, and preferably from about 10 to 20% by weight, of combined amine oxide and copper amine complex (excluding water), based upon 100% weight of total composition.
The concentrate may be diluted to a range of about 0.1 to about 5% for treating wood. Use dilutions of the composition typically comprise a biocidally effective amount of the copper amine complex and a preservative enhancing and/or waterproofing effective amount of the amine oxide. Use dilutions preferably comprise from about 0.5 to about 5.0% by weight of amine oxide and from about 0.05 to about 1.0% by weight of copper (expressed as copper oxide), based upon 100% weight of total composition.
Other adjuvants may be included in the composition as known to one of ordinary skill in the art. Other biocides, fungicides and insecticides may be include in the composition. Any organic insecticide or fungicide that can be solubilized by an aqueous amine oxide solution is suitable for use in the present composition. Suitable insecticides include, but are not limited to, chloropyrifos, folpet, captafol, captan, pyrethroids, and any combination of any of the foregoing. Suitable fungicides include, but are not limited to, iodopropargyl butylcarbamate, tributyltin oxide, 2-(thiocyanomethylthio)benzothiazole, iodosulfones, azoles, isothiazalones, and any combination of any of the foregoing.
According to one embodiment, the weight ratio of amine oxide to biocide, fungicide, or insecticide ranges from about 1:0.01 to about 1:0.25 and preferably is about 1:0.1. For example, the composition may contain cocodimethylamine oxide and chlorpyrifos at a weight ratio of about 1:0.1.
The composition of the present invention may be prepared by mixing the aqueous copper amine complex, amine oxide, solvents, and adjuvants. The mixture may be heated, e.g., to a temperature of from about 50 to about 60xc2x0 C., and/or stirred to expedite mixing.
A preferred method of preparing the composition is to mix the concentrated copper amine complex with the amine oxide followed by stirring and optional warming until the mixture is uniform. Water miscible solvents, such as alcohols, glycols, ethers, and the like, may be used to hasten solution of the components.
The copper amine complex may be prepared by methods known in the art. For example, U.S. Pat. No. 4,622,248 describes forming copper amine complexes by dissolving copper oxide in ammonia in the presence of ammonia bicarbonate. U.S. Pat. No. 4,622,248 also discloses an alternative method of preparing copper amine complexes by dissolving a mixture of copper carbonate and copper hydroxide in ethanolamine and water. The complexing amine and copper need to be charged to meet the 4 to 1 (molar) stoichiometry and thus the weight ratio of reagents will be different for each complexing amine. For amino with more than one amine group such as ethylene diamine, each amine group may be counted in the calculation.
Another embodiment of the present invention is a method for preserving and/or waterproofing a wood substrate by contacting a wood substrate with the composition of the present invention. The composition may be applied by any wood treating method known to one of ordinary skill in the art including, but not limited to, brushing, dipping, soaking, vacuum impregnation (e.g. double vacuum technique), and pressure treatment using various cycles.